1. Field of the Invention
The present invention relates to an apparatus for releasably connecting a lifting mechanism to a load. More specifically, the apparatus comprises a hollow annular body with a movable bolt within the cavity. When the bolt is in the closed position, it engages the load. The bolt is locked in the closed position until the bolt is opened by a remote release. The apparatus is especially suitable for lifting operations in connection with tilt-up panels used in the construction industry.
2. Description of the Prior Art
Prefabricated building components, including precast tilt-up panels, are widely used within the construction industry to provide a more efficient and rapid means of construction. To avoid using lifting anchors that protrude from the building components, recessed anchors were developed and have been used successfully. Such recessed anchors and their related lifting devices have been disclosed by Haeussler in U.S. Pat. No. 4,173,367, by Fricker in U.S. Pat. No. 4,173,856, and by Kelly in U.S. Pat. No. 4,580,378. The hoisting shackle with quick release attachment disclosed by Fricker in U.S. Pat. No. 3,883,170 uses a shackle formed as a hollow ring having a slot formed therein. An anchor having a first end attached to a building component has a second end that projects through the slot in the hollow ring. A curved bolt is selectively moved within the hollow ring across the slot to engage the anchor. This device uses a Bowdin cable to move the curved bolt to the open position so that the shackle may be removed from the anchor. U.S. Pat. No. 4,437,642 issued to Holt modified the Fricker shackle by elongating the operating lever. This lever arm engages a second lifting shackle while the load is being lifted, preventing the opening of the ring shackle. When the lifting line goes slack, the lifting shackle moves away from the lever arm permitting the ring shackle to open.
Notwithstanding the existence of such prior art, it remains clear that there is a need for a lifting apparatus that maintains a closed position even when slack has occurred in the lifting line between the lifting mechanism and the load. The present invention is an improvement of the apparatus disclosed by Fricker '170.